@type precond_v2() :: [
  time_bounds: Stellar.TxBuild.TimeBounds.t(),
  ledger_bounds: Stellar.TxBuild.LedgerBounds.t(),
  min_seq_num: Stellar.TxBuild.OptionalSequenceNumber.t(),
  min_seq_age: non_neg_integer(),
  min_seq_ledger_gap: non_neg_integer(),
  extra_signers: [Stellar.TxBuild.SignerKey.t()]
]

@type preconditions() :: precond_v2() | Stellar.TxBuild.TimeBounds.t() | nil

@type t() :: %Stellar.TxBuild.Preconditions{
  preconditions: preconditions(),
  type: type()
}

@type type() :: :precond_v2 | :precond_time | :none

@type valid() :: non_neg_integer() | struct() | [struct()]

@type validation() :: {:ok, valid()} | {:error, atom()}